The purpose of this note is to examine the performance of equity index funds in Taiwan using time-varying Jensen's and risk, which is generated by both the rolling and recursive regression approach. The empirical evidence indicates that the Taiwan Top50 Tracker Fund (TTT) is indeed characterized by relatively lower risk and better performance than the Taiwan Tracker Fund (TTF). The TTT serves as a worthwhile investment target for most investors. The findings also indicate that it is comparatively easier for fund managers to replicate the small index portfolios than those larger ones.